the eastern and western HKH, with relatively higher
warming in winter based on the diagnosis from
high-resolution CORDEX model outputs (Sanjay et al.
2017). The downscaled multi-RCMs analysis from CORDEX projection shows a significant warming over the HKH
as a whole and its hilly sub-regions, with a projected change
of 5.4 °C during winter and 4.9 °C during the summer
season by the end of the twenty-first century under the
high-end emissions (RCP8.5) scenario (Sanjay et al. 2017).
Projected changes in annual mean temperature over the
HKH region is also calculated using the Reliability
Ensemble Approach (REA; Box 2.4) based on the CORDEX
models. The near future (2040–2069) increase in annual
mean temperature over the HKH is projected to be 2.26 °C
± 0.45 °C (3.2 °C ± 0.58 °C) in the RCP4.5 (RCP8.5)
scenarios, respectively. The corresponding projections for
the two scenarios in the far future (2070–2099) are noted to
be 2.76 °C ± 0.61 °C (5.23 °C ± 0.91 °C), respectively. The
changes are relative to the baseline period (1976–2005).
Precipitation response to climate change is subject to
greater uncertainties, as compared to temperature changes,
particularly over the complex topographical terrains of HKH.
To better understand projected changes in precipitation, we
additionally used the multi-model ensemble (MME) from the
high-resolution (0.5° resolution) dynamically downscaled
CORDEX-SA models (Table 3.2a of Chap. 3; 16 members)
Fig. 11.5 Box whiskers of variations in surface air temperature (°C),
precipitation (mm/day) and snow (mm/day) over the HKH from the
CMIP5 projections for the different future scenarios (Annual mean
(a) and Winter season (b)). Variations in ten-year means, with respect
to the reference period (1976–2005), are presented as box whiskers
plots. Observed temperature (CRU) and precipitation (APHRODITE)
are shown during 1951–2015. Precipitation from GPCP and CMAP are
also shown during 1981–2015. Grey shade is the ensemble spread
during 1981–2015. The snow cover observation is based on the NSIDC
dataset from 1979 to 2012 (NHSC: Northern Hemisphere State of
Cryosphere, right y-axis). Note that variations in observed snow cover
extent are expressed in x 10000 km
2
. The CMIP5 projected variations
in snowfall are expressed in mm/day (left y-axis)
Table 11.1 Projected changes in mean annual precipitation (%) over HKH region with respect to 1976–2005 period
Scenario
Spatial range of annual precipitation change (%)
CMIP5
CORDEX
NEX
Near future
RCP4.5
2–8
5 –15
5–20
RCP8.5
4–15
10–20
5–25
Far future
RCP4.5
5–15
10–20
15–25
RCP8.5
10–20
15–30
20–40
11 Climate Change Over the Himalayas
213
warming in winter based on the diagnosis from
high-resolution CORDEX model outputs (Sanjay et al.
2017). The downscaled multi-RCMs analysis from CORDEX projection shows a significant warming over the HKH
as a whole and its hilly sub-regions, with a projected change
of 5.4 °C during winter and 4.9 °C during the summer
season by the end of the twenty-first century under the
high-end emissions (RCP8.5) scenario (Sanjay et al. 2017).
Projected changes in annual mean temperature over the
HKH region is also calculated using the Reliability
Ensemble Approach (REA; Box 2.4) based on the CORDEX
models. The near future (2040–2069) increase in annual
mean temperature over the HKH is projected to be 2.26 °C
± 0.45 °C (3.2 °C ± 0.58 °C) in the RCP4.5 (RCP8.5)
scenarios, respectively. The corresponding projections for
the two scenarios in the far future (2070–2099) are noted to
be 2.76 °C ± 0.61 °C (5.23 °C ± 0.91 °C), respectively. The
changes are relative to the baseline period (1976–2005).
Precipitation response to climate change is subject to
greater uncertainties, as compared to temperature changes,
particularly over the complex topographical terrains of HKH.
To better understand projected changes in precipitation, we
additionally used the multi-model ensemble (MME) from the
high-resolution (0.5° resolution) dynamically downscaled
CORDEX-SA models (Table 3.2a of Chap. 3; 16 members)
Fig. 11.5 Box whiskers of variations in surface air temperature (°C),
precipitation (mm/day) and snow (mm/day) over the HKH from the
CMIP5 projections for the different future scenarios (Annual mean
(a) and Winter season (b)). Variations in ten-year means, with respect
to the reference period (1976–2005), are presented as box whiskers
plots. Observed temperature (CRU) and precipitation (APHRODITE)
are shown during 1951–2015. Precipitation from GPCP and CMAP are
also shown during 1981–2015. Grey shade is the ensemble spread
during 1981–2015. The snow cover observation is based on the NSIDC
dataset from 1979 to 2012 (NHSC: Northern Hemisphere State of
Cryosphere, right y-axis). Note that variations in observed snow cover
extent are expressed in x 10000 km
2
. The CMIP5 projected variations
in snowfall are expressed in mm/day (left y-axis)
Table 11.1 Projected changes in mean annual precipitation (%) over HKH region with respect to 1976–2005 period
Scenario
Spatial range of annual precipitation change (%)
CMIP5
CORDEX
NEX
Near future
RCP4.5
2–8
5 –15
5–20
RCP8.5
4–15
10–20
5–25
Far future
RCP4.5
5–15
10–20
15–25
RCP8.5
10–20
15–30
20–40
11 Climate Change Over the Himalayas
213